Large Antenna Array Self-Calibration Using Mutual Coupling
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Solution Overview
Problem
Current calibration methods for large antenna array radio systems, such as 5G base stations, are inefficient and require anechoic test chambers or dedicated coupler elements, making them time-consuming and costly, and are sensitive to temperature variations and aging effects.
Innovation Solution
A self-calibration method using mutual couplings between antenna elements, where orthogonal test signals are simultaneously transmitted and received to compute amplitude and phase calibration values, eliminating the need for anechoic chambers and dedicated couplers, and allowing for efficient calibration across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an anechoic test chamber is used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The antenna array performs self-calibration by having transmit antenna elements transmit test signals that are received by receive antenna elements within the same array. The system uses its own internal structure to measure and determine scaling factors, eliminating the need for external anechoic chambers or dedicated coupler elements.
Solution Approach 2:
The invention extracts and removes the requirement for external calibration equipment (anechoic chambers, dedicated couplers) by utilizing the mutual coupling relationships that already exist between antenna elements in the array. The calibration functionality is extracted from external equipment and implemented using the antenna array's own structure.
2Measurement precision
If stepwise transmission calibration is performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The invention merges multiple calibration measurements into simultaneous operations. Multiple transmit antenna elements transmit orthogonal test signals at the same time, and multiple receive antenna elements perform measurements concurrently. The orthogonal signaling allows the system to separate and identify individual transmit signals in the combined received signals, enabling parallel calibration of multiple antenna paths simultaneously.
Solution Approach 2:
The calibration process maintains continuous useful action by having the antenna array operate in calibration mode without requiring external equipment setup. The system continuously transmits orthogonal test signals and performs measurements in an uninterrupted manner, eliminating the need for sequential setup and teardown of external calibration equipment.
3Measurement precision
If dedicated coupler elements are added, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The antenna elements serve multiple functions: they act as both transmit and receive antenna elements depending on the calibration phase. The same antenna elements used for normal communication operations are also used for calibration measurements, eliminating the need for dedicated coupler elements or separate calibration hardware.
Solution Approach 2:
The antenna array uses its own mutual coupling relationships to perform calibration measurements without requiring external coupler elements. The system leverages the natural electromagnetic coupling between adjacent antenna elements to obtain the measurement data needed for determining scaling factors.
4Measurement precision
If full bandwidth test signals are used, then measurement precision is improved, but loss of time increases due to repeated measurements
Solution Approach 1:
The invention combines full bandwidth calibration measurements into a single simultaneous operation. Orthogonal test signals that span the entire operating bandwidth are transmitted and measured in one calibration procedure, eliminating the need to repeat measurements across different frequency bands or subbands.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly reduces calibration time, is cost-effective, and can be performed frequently to adapt to temperature changes and aging effects, ensuring consistent performance without the need for expensive equipment.
Implementation Method 1
a first plurality of combined receive signals received via the second plurality of receive antenna elements, respectively, during the simultaneous transmission of the second plurality of orthogonal test signals via the second plurality of transmit antenna elements due to coupling between the second plurality of receive antenna elements and the second plurality of transmit antenna elements
Data Source
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AI summary
Systems and methods for providing efficient antenna calibration that particularly beneficial for a radio system having a large antenna array are disclosed.